Chair backrest having adjustable head and lumbar zones

ABSTRACT

Provided is a mechanism mounted in a separable head zone or a lumbar zone in either recess of a backrest of a chair. In one embodiment the mechanism comprises upper and lower cross members having pivotal centers and each cross member having one ends slidably secured to the lumbar zone or the head zone and a back board, a post having both ends slidably secured one ends of the cross members, a piston-cylinder assembly having one end fixedly coupled to the post, and two push buttons each provided on one side of the backrest and having one end coupled to the piston. Pressing the push button will extend the piston, slide the cylinder to push the post inwardly and slide one ends of the cross members inwardly, and extend the lumbar zone or the head zone from the corresponding recess.

FIELD OF THE INVENTION

The present invention relates to chairs and more particularly to an ergonomic chair (e.g., office chair) having its backrest provided with adjustable head and lumbar zones so as to accommodate users of different body portions (e.g., head and lumbar) and provide a degree of comfort thereto.

BACKGROUND OF THE INVENTION

There have been numerous suggestions in prior patents for the provision of an ergonomic chair having mechanism for adjusting height, arms, or inclined degree of backrest. However, such prior mechanisms are relatively complex in constructions, costly to manufacture, trouble-prone, and unreliable in use. Moreover, document about an ergonomic chair having its backrest provided with adjustable head and lumbar zones has not been disclosed as far as the present inventor is aware. Thus, continuing improvements in the exploitation of ergonomic chair are constantly being sought.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an ergonomic chair having its backrest provided with adjustable head and lumbar zones so as to accommodate users of different body portions (e.g., head and lumbar) and provide a degree of comfort thereto.

In one aspect of the present invention, there is provided a mechanism mounted in a separable head zone or a lumbar zone in either recess of a backrest of a chair, comprising an upper cross member comprising first and second members pivtotably intersected at their centers wherein one end of the first member is slidably secured to an elongate groove of a first bracket secured to the lumbar zone, one end of the second member is secured to a second bracket secured to the lumbar zone, the other end of the first member is secured to a third bracket secured to a back board of the backrest, and the other end of the second member is slidably secured to an elongate groove of a fourth bracket secured to the back board; a lower cross member comprising third and fourth members pivtotably intersected at their centers wherein one end of the third member is slidably secured to an elongate groove of a fifth bracket secured to the lumbar zone, one end of the fourth member is secured to a sixth bracket secured to the lumbar zone, the other end of the third member is secured to a seventh bracket secured to the back board, and the other end of the fourth member is slidably secured to an elongate groove of an eighth bracket secured to the back board; a post having one end slidably secured to the other end of the second member and the other end slidably secured to the other end of the fourth member; a piston-cylinder assembly comprising one end fixedly coupled to an intermediate portion of the post, a C-shaped member secured to the back board, a cylinder slidably fastened by the C-shaped member, a piston extended lengthwise within the cylinder and including an outwardly projected end slidably secured to the backrest, and a trigger member provided at the projected end of the piston; and two push buttons each provided on one side of the backrest and having one end coupled to the trigger member, whereby pressing one push button will move the trigger member to extend the piston from the cylinder, slide the cylinder to push the post inwardly and slide one ends of the first and third members inwardly, and extend the lumbar zone or the head zone from the corresponding recess; and urging the lumbar zone or the head zone against the back board will slide the post outwardly and slide one ends of the first and third members outwardly, and retract the lumbar zone retracted into the corresponding recess.

In another aspect of the present invention, there is provided a mechanism mounted in a separable head zone or a lumbar zone in either recess of a backrest of a chair, comprising a piston-cylinder assembly secured to the backrest and comprising a bracket secured to the lumbar zone or the head zone, a cylinder, and an extendable piston having its projected end secured to the bracket; two finger tabs provided on one side of the backrest; and two wires each interconnected one of the finger tabs to the piston, whereby pressing one finger tab will extend the piston from the cylinder via one wire, and extend the lumbar zone or the head zone from the corresponding recess; and urging the lumbar zone or the head zone against the backrest will retract the piston into the cylinder, and retract the lumbar zone or the head zone into the corresponding recess.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description taken with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a first preferred embodiment of chair according to the invention;

FIG. 2 is an exploded view of a mechanism for adjusting the lumbar zone of backrest shown in FIG. 1;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1 where the mechanism is in a retracted position;

FIG. 4 is a view similar to FIG. 3 where the mechanism is in an extended position;

FIG. 5 is a side view schematically depicting a person sitting on the chair with both mechanisms in the extended positions;

FIG. 6 is a perspective view of a second preferred embodiment of chair according to the invention;

FIG. 7 is an exploded view of a mechanism for adjusting the lumbar zone or the head zone of backrest shown in FIG. 6; and

FIG. 8 is a sectional view taken along line 8-8 of FIG. 6 where the mechanism is in an extended position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 5, there is shown a chair 10 (e.g., office chair) having its backrest 11 formed of elastomeric material for providing a seated person with a degree of comfort in a slightly lying position. The backrest 11 is provided with adjustable, separable head zone 20 and lumbar zone 30 in accordance with a first preferred embodiment of the invention. Note that a second mechanism for adjusting the head zone 20 has the same characteristics as a first mechanism for adjusting the lumbar zone 30. Thus, for the sake of brevity the following description is about the first mechanism only.

A rectangular recess 12 is formed in the backrest 11. The recess 12 has a depth to expose a back board 13. The lumbar zone 30 is a member of parallelepiped and is shaped to receive in the recess 12. An upper first cross member comprises two members 31 and 31′ pivtotably intersected at their centers by a pin. One end of one member 31′ is slidably secured to an elongate groove 37 of a first bracket 35 which in turn is secured to the lumbar zone 30 by fasteners. One end of the other member 31 is secured to a second bracket 33 which in turn is secured to the lumbar zone 30 by fasteners. The other end of one member 31′ is secured to a third bracket 34 which in turn is secured to the back board 13 by fasteners. The other end of the other member 31 is slidably secured to an elongate groove 37 of a fourth bracket 36 which in turn is secured to the back board 13 by fasteners.

Likewise, a lower second cross member comprises two members 32 and 32′ pivtotably intersected at their centers by a pin. One end of one member 32′ is slidably secured to an elongate groove 37 of a first bracket 35′ which in turn is secured to the lumbar zone 30 by fasteners. One end of the other member 32 is secured to a second bracket 33′ which in turn is secured to the lumbar zone 30 by fasteners. The other end of one member 32′ is secured to a third bracket 34′ which in turn is secured to the back board 13 by fasteners. The other end of the other member 32 is slidably secured to an elongate groove 37 of a fourth bracket 36′ which in turn is secured to the back board 13 by fasteners. A post 38 has one end slidably secured to the other end of the other member 31 at the groove 37 of the fourth bracket 36 and the other end slidably secured to the other end of the other member 32 at the groove 37 of the fourth bracket 36′. A member 42 of C-shaped is fixedly coupled to an intermediate portion of the post 38. The member 42 is provided at one end of a piston-cylinder assembly 40. A piston 41 is extended lengthwise within the piston-cylinder assembly 40 and has an outwardly projected end slidably secured to one side of the backrest 11 by a fastening member 43. The projected end of the piston 41 is formed as a trigger member 44 which in turn is coupled to a push button 45 provided externally of the backrest 11 for ease of operating by a finger. A C-shaped fifth bracket 39 is adapted to slidably secure the piston-cylinder assembly 40 to the back board 13.

An extend operation of the first mechanism will be described in detailed below. A user may press the push button 45 to extend the piston 41 from the piston-cylinder assembly 40 via the trigger member 44. Also, the piston-cylinder assembly 40 slides through the fifth bracket 39 to push the post 38 inwardly. And in turn the post 38 slides inwardly and thus one ends of members 31′ and 32′ slide inwardly from the position shown in FIG. 3 to the position shown in FIG. 4. As an end, the lumbar zone 30 is extended from the recess 12. Such adjustment can be continued until a desired contact (i.e., a degree of comfort) of the lumbar zone 30 with the back of a seated person is reached. It is obvious that a retraction operation of the first mechanism can be done by a person strongly urging his/her back against the lumbar zone 30 for sliding the post 38 outwardly and thus sliding one ends of members 31′ and 32′ outwardly from the position shown in FIG. 4 to the position shown in FIG. 3. As an end, the lumbar zone 30 is retracted into the recess 12.

Referring to FIGS. 6, 7 and 8, there is shown a chair 50 according to a second preferred embodiment of the invention. The differences between the first and the second preferred embodiments, i.e., the characteristics of the second preferred embodiment are detailed below. A head zone 60 is provided on an upper recess 52 of a backrest 51. A lumbar zone 70 is provided on a lower recess 53 of the backrest 51. A piston-cylinder assembly 80 is secured to the backrest by fasteners and comprises a bracket 82 secured to the lumbar zone 70 by fasteners and an extendable piston 81 having its projected end secured to the bracket 82 by a fastener. In an extending operation of the lumbar zone 70 by manipulating the first mechanism a user may press one finger tab 84 to extend the piston 81 outwardly via one interconnecting wire 85. As a result, the lumbar zone 70 extends from the recess 53. Note that in an extending operation of the head zone 60 by manipulating the first mechanism a user may press the other finger tab 85 to extend the piston 81 outwardly via the other interconnecting wire 85.

While the invention herein disclosed has been described by means of specific embodiments, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope and spirit of the invention set forth in the claims. 

1. (canceled)
 2. A mechanism mounted in a separable head zone or a lumbar zone in either recess of a backrest of a chair, comprising: a first piston-cylinder assembly secured to the backrest and further comprising a bracket secured to the lumbar zone, a first cylinder, and a first extendable piston having its projected end secured to the bracket; a second piston-cylinder assembly secured to the backrest and comprising a bracket secured to the head zone, a second cylinder, and a second extendable piston having its projected end secured to the bracket; two finger tabs provided on one side of the backrest; and two wires, each interconnecting one of the finger tabs to one of the pistons, whereby pressing one of the finger tabs will extend one of the pistons from the cylinder via one wire, and extend the lumbar zone or the head zone, respectively, from the corresponding recess; and urging the lumbar zone or the head zone against the backrest will retract the piston into the cylinder, and retract the lumbar zone or the head zone into the corresponding recess. 